1. Field of the Invention
The present invention relates to a multilayer capacitor, and more particularly to a multilayer capacitor capable of easily acquiring an equivalent series resistance of a desired value.
2. Description of the Related Art
In recent years, central processing units (CPUs) provided in digital electronic equipment have been moving toward lower voltages and higher load currents. Therefore, in the power source for supplying an electric power to the CPU, it is difficult to keeping voltage fluctuations within an allowable range to a rapid change of the load current supplied to the CPU.
FIG. 1 shows a conventional power circuit 200 for a CPU 203. The power circuit 200 includes a multilayer ceramic capacitor 201 called a decoupling capacitor that is connected to a power source 202. The multilayer capacitor 201 is provided with an equivalent series resistance (ESR) and an equivalent series inductance (ESL). During transient changes in a load current I flowing from the power source 202 to the CPU 203, a current is supplied from the multilayer capacitor 201 to the CPU 203 in order to regulate voltage fluctuations in the power source 202.
Further, as the operating frequency in today's CPUs continues to improve, there is an increasing demand for larger load currents and a fast transient response. The ESR and ESL of the multilayer capacitor 201 have a great influence on voltage fluctuations in the power source 202. It is well known in the art that the effects of the ESR and ESL on voltage fluctuations in the power source 202 can be decreased by reducing the ESL and increasing the ESR. Various types of multilayer capacitors capable of reducing the ESL and increasing the ESR have been proposed.
For example, Japanese unexamined patent application publication No. 2002-164256 proposes a multilayer capacitor. The multiplayer capacitor has a dielectric element with a plurality of stacked sheet-like dielectric layers, interlayer electrodes disposed between adjacent dielectric layers, and a plurality of external electrodes connected to each interlayer electrode. Each interlayer electrode is configured of an internal electrode and an extraction electrode. Each internal electrode is shaped substantially alike in a continuous shape having a pair of parallel parts extending parallel to each other. The positions of first and second ends of the internal electrodes are different for each electrode in the stacking direction of the dielectric layers. Further, the extraction electrodes extend from the first end of each internal electrode to the external electrodes and are connected to the external electrodes.
However, while conventional multilayer capacitors have been successful in reducing ESL and increasing ESR, they have difficulty setting the ESR to a value appropriate for a prescribed ESL. If the ESR value is too small for the prescribed ESL value, ringing can occur; if too large, a charging/discharging current is inhibited.